Process of treating skins or hides previous to tanning



Patented Jan. 14, 1930 UNITED STATES PATENT OFFICE" W H. ALLEN, OFDETROIT, MICHIGAN, ASSIGNOR TO LEATHER MAKERS PROCESS COMPANY, OFDETROIT, MICHIGAN, A CORPORATION OF MICHIGAN PROCESS OF TREATING SKINSOB HIDES PREVIOUS TO TANNING Io Drawing. Application fled Inly 8,

This invention relates to treatment of untanned skins and hides.

One of the customary methods of disinfecting raw skins and hides is thestandard method authorized by the U. S. Government involving the soakingof the hides either green (fresh), salted or dried in a solutioncontaining common salt and hydrochloric acid. In using such a method, ithas been found that after disinfection, the skins or hides contain mostof the free hydrochloric acid and, upon washing, there is alwa sproduced more or less swelling of the hi es due .to more or lesshydrolysis of the leather substance, which hydrolysis is quitedetrimental to the qualitE of the leather produced from such hides. venwhen the washing is omitted and the hides are placed in the usualaqueous solution of calcium sulphide and hydrate,

the same action occurs.

Among the objects of the present invention therefore, is to overcomesuch objections and prevent or at least reduce to a substantiallynegligible amount, the hydrolysis caused by the presence of this freematerial.

Other objects will readily occur to those skilled in the art uponreference to the following description.

In carrying out the present process, the

skins or hides are disinfected in the usual manner with the brinecontaining hydrochloric acid, but instead of removing the hides from thedisinfection solution, and washing or proceeding in the usual manner,

the acid of the disinfecting solution is neutralized while the hides arestill therein, by

' the addition to such solution containing the hides, of'sufiicient limeor other alkali such as caustic soda or soda ash, to neutralize the freeacid present. I

In the addition of the lime or alkali, there is, of course, interactionbetween the lime and the acid brine and there is always formed,

when lime is used, some calcium chloride due to the neutralization ofthe acid.

After the neutralizing step, therefore, the hides may be removed fromthe'solution and washed to remove the salt, calcium chloride,

and other reaction products and, in such 1928. Serial No. 290,050.

If it is not desired to send the skins directly into the tanning processor other use, the washing step may be omitted and the sterilized skinsdrained of the neutralized brine, salted and stored or shipped as thecase may be.

Now having described the invention and the preferred form of embodimentthereof, it is to be understood that the said invention is to be limitednot bythe specific details herein set forth but only by the scope of theclaims which follow.

I claim 1. The process of treating skins or hides preparatory totanning, which comprises disinfecting t ing them in a solutioncontaining common sa t and hydrochloric acid, then neutralizing thesolution with the hides therein by the addition of suficient akalinematerial to neutralize the free acid, then removing the hides andwashing to substantially eliminate the contained salts.

2. The process of treating skins or hides preparatory to tanning, whichcomprises disinfecting the said skins or hides by immersing them in asolution containing common salt and hydrochloric acid, then neutralizingthe solution with the hides therein by the addition of suflicienthydrated lime to neutralize the free acid, then removing the hides andwashing to substantially eliminate the contained salts.

3. In a treatment of skins or hides preparatory to tanning, disinfectingsaid skins or hides in a solution containing free hydrochloric acid,neutralizing the'acid in the hides by the addition thereto of a.suitable alkaline material and washing the soluble salts from the hides.

4. In a treatment of skins or hides preparatory to tanning, disinfectingsaid skins or hides in a solution containing free hydroc said skins orhides by immerschloric acid, neutralizing the acid in the hides by theaddition thereto of lime and washing the soluble salts from the hides.

5'. In a treatmentrof skins or hides reparatory to tanning, disinfectingsaid as or hides in a solution containing free hydrochloric acid andneutralizing the acid in the hides by the addition thereto of a suitablealkaline material.

WILLIAM H. ALLEN.

